<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>innerHTML</title>
</head>
<body>
  <div id="testdiv">
    <p>This is <em>my</em> content.</p>
  </div>
  <script type="text/javascript">
    window.onload = function() {
      var testdiv = document.getElementById("testdiv");
      alert(testdiv.innerHTML);
      testdiv.innerHTML = "Hello <em>World!</em>";
    }
  </script>
</body>
</html>
